Have a nice sized bucktail that I got last fall. I dried it by the woodstove all winter with salt on it. I am not happy with the whiteness of the white hair. What is the best way to wash them without loosing the hair and should I be treating them with something other than kosher salt?

When I used to play around with tails, I found it was easier to wash them when they were fresh [ after de-boning ] with dish detergent and water. Then I would soak them in Liquid -Tan [ taxidermy supply houses carry it ] pull them out and dry with a hair dryer and fine comb or brush........... or after you wash them they can be sprinkled [ fur & all ] with Borax [ found in the laundry isle at most supermarkets ] then blow dry and comb leaving them slighty damp, then applying Borax liberally to the flesh.....I found both methods better than using Kosher salt.

I've always bought my bucktail, it sounds like you've got one that is off white - and you want to get it pure white.
I doubt you would be able to do that by washing it. You could dye it white or maybe there is a way to bleach it white.
I've been told to use borax if the skin hasn't dried or gets funky on you.

Leave it out in the sun the sun bleaches everything white

After the tail has cured, so there is "no hair slipping"....... you can dye them any color you want using a permanent dye....... again when you take them out of the solution, use a hair drier and a brush or comb to make them purty..................